1. Field of the Invention
The present invention relates to a washing and drying machine and to a clothes dryer. More specifically, according to one aspect, the present invention relates to an improvement of an apparatus for providing fragrance to clothes dried by the washing and drying machine, and according to another aspect, the present invention is directed to a washing and drying machine and a clothes dryer that can provide clothes finished as if they were sun-dried, at the end of the drying step.
2. Description of the Related Art
A clothes dryer drying clothes as an object has been conventionally known. Further, a washing and drying machine that washes and dries clothes in one rotating tank has also been known.
In connection with the one aspect, a clothes dryer having a device for irradiating the clothes with ultra-violet ray has been proposed, as disclosed, for example, in Japanese Patent Laying-Open No. 2-57300. The clothes dryer includes a rotary drum turning the clothes, a circulating path circulating hot air in the drum, and irradiating means for irradiating the inside of the drum with ultra-violet ray, in which the irradiating means irradiates at least in a reduced rate drying step in the process of drying the cloths and in following steps. In the clothes dryer, the ultra-violet ray is emitted from the irradiating means mainly in the reduced rate drying step in which the clothes are almost dry, in the process of drying the clothes. Therefore, ultra-violet ray is not much deactivated by moisture, and hence, it is described that sterilization by the ultra-violet ray from the irradiating means is effectively attained.
In the clothes dryer, however, ultra-violet ray is emitted for sterilization of the clothes, and therefore, it is necessary to irradiate the clothes with ultra-violet ray for a long time at a high temperature. Though highest effect of sterilization can be attained when the clothes are irradiated with ultra-violet ray from before the reduced rate drying step until the end of drying, it is described in this laid-open application that such a manner of irradiation is not very preferable considering damage to the clothes and efficiency of operation.
Further, a washing and drying machine incorporating ultra-violet ray irradiating means for irradiating a textile product with ultra-violet ray to have the textile product with sun-dried fragrance has also been proposed, as disclosed in Japanese Patent Laying-Open No. 2002-275756. In the washing and drying machine, laundry in the rotary tank or textile product to be dried is irradiated with ultra-violet ray to provide sun-dried fragrance with the textile product, and the machine may have draining function as desired, and hot air is introduced as desired, for washing and drying.
Textile product, however, is said to have stronger fragrance at the end of drying if the process described above is performed with the textile product having some moisture. In order to show this effect, this laid-open application describes experimental results obtained by drying wet clothes while emitting ultra-violet ray for a long period of time. When exposed to the ultra-violet ray for a long time, clothes are naturally damaged, which may possibly affect the fragrance.
In connection with another aspect, the principle of aromatizing cloth is described in “SAISHIN KOUSUI JIJYOU” (The Aspect of Modern Fragrances) by Ryoichi KOMAKI, KORYO, Japan Perfumery & Flavoring Association, June 2002, Vol. 214, supplementary edition. Here, it is described that volatile components become loose from fibers of sun-dried laundry, because of the functions of ultra-violet ray and radiant heat of sunlight. Specific examples of the volatile components listed in this reference include saturated and unsaturated chain aldehydes with carbon number of 6 to 15 as main components, and ketones, alcohols and some fatty acids.
Japanese Patent Laying-Open No. 2002-285189 discloses a perfume component that recollects washed and dried clean cotton fabric. The inventors of the present invention boiled off odor components of towels, sun-dried the towels and analyzed volatile components emitted from the towels by gas chromatography, and actually, similar substance could be detected.
As described above, however, clothes and washing tank are damaged when the clothes are irradiated with ultra-violet ray. Cotton is decomposed by ultra-violet ray and radiant heat, and mainly, chain hydrocarbons and saturated and unsaturated aldehydes with carbon number of 6 to 15, as well as ketones, alcohols and some fatty acids are isolated therefrom. From a towel that was irradiated by a sterilizing lamp having a peak in UVC wave (by way of example, wavelength=260 nm) for 10 minutes at an adjusted temperature of 40° C., larger amount of volatile substances can be obtained than from a sun-dried towel. From this result, it can be concluded that UVC wave irradiation potentially damages fibers. Sensory analysis also revealed that longer time of irradiation noticeably resulted in odor of a different nature. Therefore, time and temperature control is essential when UVC wave irradiation is employed.
A light source having a peak in UVA wave (by way of example, wavelength=315 to 400 nm), such as a black light or a chemical lamp also causes odor of a different nature from the clothes as in the case of UVC wave, when used for a long time.
According to a further aspect, Japanese Patent Publication No. 5-46239 discloses a clothes dryer including a drum rotatably supported in a main body, an air blower introducing drying air to the drum, a heater for drying an object, a motor driving the drum and the air blower, a ultra-violet ray irradiating lamp provided in the drum, and a detecting device feeding power to the ultra-violet ray irradiating lamp when temperature in the drum rises rapidly in a later stage of the drying process. In the clothes dryer, the object can be dried as the temperature of the rotating tank is increased. This also applies to a washing and drying machine. In order to dry the object more quickly and reliably, the temperature of the rotary tank may be set higher during the drying process. As a result, the temperature of the object in the rotary tank becomes higher than when sun-dried.
When the dried object is taken out from the rotary tank at the end of drying process and the temperature of the object is too high or too low, the sun-dried feeling cannot be enjoyed.
That ultra-violet irradiation of clothes as an object of drying may promote degradation of fibers in the cloths is described in “Research regarding the degradation of the fiver by the ultra-violet rays irradiation of wave length 253.7 nm”, Shin-ichirou HIRAIDE [on-line] [searched May 17, 2004], at <http://www.nagano-it.go.jp/jyouhou/report/2000/0013.pdf>.    [Patent Document 1] Japanese Patent Laying-Open No. 2-57300    [Patent Document 2] Japanese Patent Laying-Open No. 2002-275756    [Patent Document 3] Japanese Patent Laying-Open No. 2002-285189    [Patent Document 4] Japanese Patent Publication No. 5-46239    [Non-Patent Document 1] “SAISHIN KOUSUI JIJYOU” (The Aspect of Modern Fragrances) by Ryoichi KOMAKI, KORYO, Japan Perfumery & Flavoring Association, June 2002, Vol. 214, supplementary edition    [Non-Patent Document 2] “Research regarding the degradation of the fiver by the ultra-violet rays irradiation of wave length 253.7 nm”, Shin-ichirou HIRAIDE [on-line][searched May 17, 2004], at <http://www.nagano-it.go.jp/jyouhou/report/2000/0013.pdf>.